Papers by Ali F. Al-rawaf
Iraqi Journal of Science
In this paper, a numerical analysis was carried out using finite element method to analyse ... more In this paper, a numerical analysis was carried out using finite element method to analyse the mechanisms for streamer discharges. The hydrodynamic model was used with three charge carriers equations (positive ion, negative ion and electron) coupled with Poisson equation to simulate the dynamic of streamer discharge formation and propagation. The model was tested within a 2D axisymmetric tip-plate electrodes configuration using the transformer oil as the dielectric liquid. The distance between the electrodes was fixed at 1 mm and the applied voltage was 130 kV at 46 ns rising time. Simulation results showed that the time has a clear effect on the streamer propagation along the symmetry axis. In addition, it was observed that the highest value of the voltage was recorded at 46 ns and the minimum voltage required for insulation breakdown was 112 kV at 200 ns. It was revealed that the streamer velocity recorded the highest value when the streamer reaches the plate electrode and t...
INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING ICCMSE 2021
The optical properties of mawsonite Cu 6 Fe 2 SNS 8 [CFTS] thin films effected by red laser irrad... more The optical properties of mawsonite Cu 6 Fe 2 SNS 8 [CFTS] thin films effected by red laser irradiation deposited via semi-computerized spray pyrolysis technique
Journal of physics, Aug 1, 2022
To reveal the impact of formation and development of the streamer discharge on the dielectric liq... more To reveal the impact of formation and development of the streamer discharge on the dielectric liquid formed between pin-plate electrodes, a numerical model of transformer oil discharge in the electrode system is built which is based on the continuity equations coupled with Poisson's equation. The influence of applied impulse voltage parameters such as rise time and voltage magnitude on the formation and development of the streamer discharge is evaluated in this model. In addition, the characteristic of the streamer discharge such as streamer velocity, electric field, and radius of streamer head have been investigated. Modeling results reveal that the higher impulse voltage amplitude form streamer discharges with longer paths, thicker columns, higher velocity, and greater radius. In addition, we find that the radius of the streamer head is greatly affected by the percentage of the predetermined electric field tube at the head, and slightly affected when streamer length increased. Modeling results also showed that the rise times had a clear effect on the radius streamer discharge and the distribution of electric fields.
International Shipbuilding Progress, 1959
Tre tipi di ipotetica o due? considerazioni sul periodo ipotetico nella lingua italiana abstact t... more Tre tipi di ipotetica o due? considerazioni sul periodo ipotetico nella lingua italiana abstact the italian "periodo ipotetico" (a conditional clause or hypothetical phrase) is a structure composed of two clauses. the main one is introduced chiefly by se and it indicates the condition (or supposition) on which something else is dependent (the other clause). many canonical grammar books assert that there are three types of hypothesis/consequence situations: real, unlikely and no longer possible. the aim of this article is to disprove this traditional thesis. with a couple of examples, it is shown that there are in fact only two types of ''periodo ipotetico''. keywords Hypothetical phrase, types of hypothesis / consequence situations. il periodo ipotetico è un costrutto condizionale costituito da due proposizioni, una sovraordinata, detta apodosi, e una subordinata, detta protasi, inscindibilmente connesse sia sul piano grammaticale che su quello logico. la protasi ipotizza la condizione da cui dipende o potrebbe dipendere la realizzazione di ciò che viene espresso nell'apodosi (l. se r ia n n i, 1991). l'apodosi e la protasi possono essere costituite da proposizioni coordinate, e l'apodosi può dipendere a sua volta da un'altra proposizione. l'operatore di subordinazione della protasi, per eccellenza, è se, ma possono essere usate altre congiunzioni o locuzioni congiuntive, come qualora, nel caso che, a condizione che, ecc. secondo la tradizionale classificazione, ispirata alla tripartizione latina fra casus realis, cassus possibilis e casus irrealis, nella lingua italiana si distinguono tre tipi di periodo ipotetico, della realtà, della possibilità e della irrealtà in correlazione ai modi e ai tempi che si usano nella protasi e nell'apodosi. in base a que
Journal of Theoretical and Applied Physics, 2018
Non-thermal atmospheric-pressure plasma jet represents an excellent approach for the decontaminat... more Non-thermal atmospheric-pressure plasma jet represents an excellent approach for the decontamination of bacteria. In this paper, we want to improve and characterize a non-thermal plasma jet to employ it in processes of sterilization. The electrical characteristics was studied to describe the discharge of the plasma jet and the development of plasma plume has been characterized as a function of helium flow rate. Optical emission spectroscopy was employed to detect the active species inside the plasma plume. The inactivation efficiency of non-thermal plasma jet was evaluated against Staphylococcus aureus bacteria by measuring the diameter of inhibition zone and the number of surviving cells. The results presented that the plasma plume temperature was lower than 34 C at a flow rate of 4 slm, which will not cause damage to living tissues. The diameter of inhibition zone is directly extended with increased exposure time. We confirmed that the inactivation mechanism was unaffected by UV irradiation. In addition, we concluded that the major reasons for the inactivation process of bacteria is because of the action of the reactive oxygen and nitrogen species which formed from ambient air, while the charged particles played a minor role in the inactivation process.
A dielectric barrier discharge (DBD) plasma jet is widely used in different applications such as ... more A dielectric barrier discharge (DBD) plasma jet is widely used in different applications such as biomedical forsterilization, in this work, DBD plasma jet operated at atmospheric pressure and room temperature is designed. The inactivation efficiency of DBD plasma jet is evaluated against staphylococcus aureus bacteria with different time exposure. The effect of gas flow rate and irradiation time on the gas temperature is studied because ionized gas temperature is important factor in bacteria treatment. Optical emission spectroscopy (OES) is investigated to determine the plasma parameters such as electron temperature and electron density. Also, OES are used to detect the active species present inside the plume of plasma. Results showed that the applied voltage play an important role in increasing the electron density which increasing the amount of active species. The area of growth inhibition zone directly extendedwith increased the exposure time of DBD plasma jet. From these results...
AENSI Publication, 2017
Staphylococcus aureus bacteria by a dielectric barrier discharge plasma jet. ABSTRACT A dielectri... more Staphylococcus aureus bacteria by a dielectric barrier discharge plasma jet. ABSTRACT A dielectric barrier discharge (DBD) plasma jet is widely used in different applications such as biomedical forsterilization, in this work, DBD plasma jet operated at atmospheric pressure and room temperature is designed. The inactivation efficiency of DBD plasma jet is evaluated against staphylococcus aureus bacteria with different time exposure. The effect of gas flow rate and irradiation time on the gas temperature is studied because ionized gas temperature is important factor in bacteria treatment. Optical emission spectroscopy (OES) is investigated to determine the plasma parameters such as electron temperature and electron density. Also, OES are used to detect the active species present inside the plume of plasma. Results showed that the applied voltage play an important role in increasing the electron density which increasing the amount of active species. The area of growth inhibition zone directly extendedwith increased the exposure time of DBD plasma jet. From these results, we believe that the main reasons for the inactivation of microorganisms are the reactive species (RONS) which creating from the surrounding air.
Springer Berlin Heidelberg, 2018
Non-thermal atmospheric-pressure plasma jet represents an excellent approach for the decontaminat... more Non-thermal atmospheric-pressure plasma jet represents an excellent approach for the decontamination of bacteria. In this paper, we want to improve and characterize a non-thermal plasma jet to employ it in processes of sterilization. The electrical characteristics was studied to describe the discharge of the plasma jet and the development of plasma plume has been characterized as a function of helium flow rate. Optical emission spectroscopy was employed to detect the active species inside the plasma plume. The inactivation efficiency of non-thermal plasma jet was evaluated against Staphylococcus aureus bacteria by measuring the diameter of inhibition zone and the number of surviving cells. The results presented that the plasma plume temperature was lower than 34 C at a flow rate of 4 slm, which will not cause damage to living tissues. The diameter of inhibition zone is directly extended with increased exposure time. We confirmed that the inactivation mechanism was unaffected by UV irradiation. In addition, we concluded that the major reasons for the inactivation process of bacteria is because of the action of the reactive oxygen and nitrogen species which formed from ambient air, while the charged particles played a minor role in the inactivation process.
Books by Ali F. Al-rawaf
LAP LAMBERT Academic Publishing, 2018
Recently, the atmospheric pressure non-thermal plasma has attracted great attention in biomedical... more Recently, the atmospheric pressure non-thermal plasma has attracted great attention in biomedical applications due to the advantages of high efficiency, safety, no toxic residue and low cost. In this work, a homemade plasma jet system was constructed. The system which used in this work was a dielectric barrier discharge (DBD) type atmospheric pressure plasma jet (APPJ). It was applied to generate a non-thermal plasma using an alternating current (AC) power supply with two types of noble gases (argon and helium).
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Papers by Ali F. Al-rawaf
Books by Ali F. Al-rawaf